Tulsa County District Attorney Steve Kunzweiler filed the charge less than a week after officer Betty Shelby shot and killed 40-year-old Terence Crutcher on Sept. 16. Kunzweiler said arrangements were being made for Shelby's surrender.

"I do not know why things happen in this world the way they do," Kunzweiler said, adding that he determined first-degree manslaughter the appropriate charge. "We need to pray for wisdom and guidance."

Dashcam and aerial footage of the shooting and its aftermath showed Crutcher walking away from Shelby with his arms in the air. The footage does not offer a clear view of when Shelby fired the single shot that killed Crutcher. Her attorney has said Crutcher was not following police commands and that Shelby opened fire when the man began to reach into his SUV window.

But Crutcher's family immediately discounted that claim, saying the father of four posed no threat to the officers. They also pointed to an enlarged photo from police footage that appears to show Crutcher's window was rolled up. And police said Crutcher did not have gun on him or in his vehicle.

Among the definitions in Oklahoma for first-degree manslaughter is a killing "perpetrated unnecessarily either while resisting an attempt by the person killed to commit a crime, or after such attempt shall have failed."

If convicted, Shelby could face a minimum of four years in prison.

Shelby, who joined the Tulsa Police Department in December 2011, was en route to a domestic violence call when she encountered Crutcher's vehicle abandoned on a city street, straddling the center line. Shelby did not activate her patrol car's dashboard camera, so no footage exists of what first happened between the two before other officers arrived.

The police footage shows Crutcher approaching the driver's side of the SUV, then more officers walk up and Crutcher appears to lower his hands and place them on the vehicle. A man inside a police helicopter overhead says: "That looks like a bad dude, too. Probably on something."

The officers surround Crutcher and he suddenly drops to the ground. A voice heard on police radio says: "Shots fired!" The officers back away and Crutcher is left unattended on the street for about two minutes before an officer puts on medical gloves and begins to attend to him.

Earlier this year, a former volunteer deputy with the Tulsa County Sheriff's Office was sentenced to four years in prison after he was convicted of second-degree manslaughter in the shooting death of Eric Harris.